1. Field of the Invention
The present invention generally relates to an apparatus and method for lifting objects by flotation from beneath the earth's surface or to elevations above the earth's surface within at least one single shaft structure. More specifically, the present invention provides an apparatus and method for conveying objects within at least one multiple chamber single shaft structure positioned beneath the earth's surface or above the earth's surface, and elevating and descending objects within the shaft structure by employing fluid buoyancy.
2. Description of the Related Art
A persistent and formidable challenge in mining and related industries is implementing cost effective, efficient and reliable devices and methods for lifting objects either from beneath the earth's surface or to elevations above the earth's surface. For instance, currently within the underground mining industry, demonstrably inefficient and relatively costly methods and devices are employed to lift rock and other objects from subsurface levels to above the earth's surface. In vertical lifting environments, using wire rope hoisting for elevating loads of objects and lowering containers (from which objects were emptied) is a frequently employed method of transporting those objects from and/or containers to beneath the earth's surface. However, hoisting materials either individually or by load in existing vertical shafts is often inordinately space consuming, time consuming, costly, and consequently inefficient. Vertical shaft hoisting generally requires an entire shaft compartment to lift a single load contained in a bucket or similar container, and additionally requires considerable time to lower the container back down the same shaft compartment to complete the hoisting cycle of a single container. Moreover, vertical shaft hoist lifting devices and methods require the use of relatively expensive equipment, including hoists, wire rope, and corresponding mechanical parts, which are not only high maintenance, but also demand frequent replacement as a consequence of normal wear and tear. In high frequency or high load density mining conditions, repair and replacement costs often increase exponentially. The relatively high costs of energy required to operate vertical hoist shafts are largely a function of load density, and the attendant amount of energy required to offset the friction of various moving parts required to elevate each load of materials.
Existing methods for lifting objects within shafts positioned at an incline either beneath or above the earth's surface involve shortcomings similar to those previously identified with respect to vertical lifting environments. For instance, conveyors, trams, trucks and other such haulage equipment are commonly employed to incline lift objects within multiple shaft structures. Such incline lifting equipment often requires even more moving parts and mechanical operation in comparison to vertical hoisting equipment, and often includes significant manual labor efforts to complete each mining cycle.
Apparent attempts to alleviate some of the disadvantages associated with existing vertical and incline lifting technologies have resulted in devices and methods embodying similarly disadvantageous characteristics, and in some instances substantially more problematic operational components. U.S. Pat. No. 4,247,229 to Evans represents one such attempt. The Evans Patent discloses an underground mining method and apparatus employing at least two separate downwardly descending shafts connected by at least one lateral opening incorporating a series of conveyors and moveable doors to facilitate container movement underground. One shaft is required to receive an ore carrier, which passes through a moveable door opening into a compartment for loading, and through a second moveable door opening into the second shaft. The second shaft is required to elevate the loaded ore carrier to the earth's surface. The apparent structural, operational and economic demands of employing two or more separate shafts to complete a mining cycle are most likely significant. Ostensibly, not only must at least two separate shafts be drilled or existing parallel shafts located and rehabilitated, but each shaft must be linked by the elaborate lateral opening connecting the multiple shafts, which presumably incorporates expensive equipment and corresponding maintenance and repair.
Thus, a need exists for a lifting apparatus and method capable of elevating animate and inanimate objects from beneath the earth's surface or to locations above the earth's surface and accordingly returning containers for reloading, preferably within a single shaft structure employing fluid buoyancy to elevate and lower containers and corresponding objects.